Mode of operation
Feed water is flowing upward through the filter bed. Filtrate is discharged at the top. Solids are retained and if applicable biomass converts organic components. Filter sand is continuously sucked into the lower end of the airlift and transported vertically towards the sand washer at the top of the filter. In order to achieve this only a small amount of compressed is required to run the airlift. Sand is washed continuously by using a small volume of filtrate. If required, process air is injected into the filter bed to create oxic operating conditions for the biomass to grow.